Measurement of muscle fibre conduction velocity in the human genioglossus muscle

The upper airway is actively held open by skeletal muscles. This mechanism fails repeatedly during sleep in patients with obstructive sleep apnea syndrome (OSAS), and the airway becomes obstructed. Only with a brief arousal from sleep can the patient resume breathing. The genioglossus (GG) muscle has a role in maintaining and restoring upper airway patency, as it is the primary protrudor of the tongue. The GG is known to have an altered fibre type composition in OSAS patients, having a higher proportion of fast-twitch, fatiguable, type II fibres. Therefore the study of GG fatigue is of interest in OSAS. One of the main correlates of peripheral fatigue is a reduction in the conduction velocity (CV) of muscle fibres. Presented in this paper are the results from measuring CV in the GG using a specially designed intra-oral surface electrode array.